Well.....Lavender 'Lady' is the only one I know of that is even marginally hardy in zone 5. Lavender is not easy to grow in my opinion, it demands very well drained soil, and excellent air circulation. It doesn't do well in areas that have humid summers. I found one variety ('Munstead') that one of my sources said was hardy to zone 5, and then other sources said the same variety was hardy to zone 6! There is also a variety called 'Provence' that may perform in zone 5. This is a plant I wouldn't push it with, if the zone is "iffy", stick with the more definitive one. If you want to give it a shot, try 'Lady'. It is available from Burpee at 1-800-888-1447.